Relationship between coking pressure and displacement of oven wall during carbonization in coke oven was investigated at Hokkai No. 6 coke oven battery (preheated-coal charging system). Determination was performed at both a superannuated oven chamber after 26 years from start and a sturdy oven chamber after a year from replacement of oven top, entire walls and oven sole. Wall displacement was observed when the internal gas pressure of plastic layer at oven center became the maximum in both oven chambers. The wall displacement increased in proportion to the internal gas pressure of plastic layer at oven center, and the displacement at superannuated oven per maximum gas pressure was larger than the one at sturdy oven. The pushing force (maximum electric current of pushing machine) greatly changed according to gas pressure of plastic layer at superannuated oven compared with the one at sturdy oven. The conclusion of this study is that the wall displacement by coking pressure greatly influences the pushing force of coke cake at superannuated oven chamber.